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PubMed2004

Electroanatomic mapping of the right atrium with a right atrial basket catheter and three-dimensional intracardiac echocardiography.

The ablation of arrhythmias progresses towards an approach based upon application of linear lesions between nonconducting anatomic/electrical areas. Hence the identification of detailed anatomy together with electrical behavior becomes increasingly important. This study aims to achieve true electroanatomic mapping by the use of three-dimensional intracardiac imaging of the right atrium combined with use of a right atrial basket to obtain detailed electrical information. We studied nine patients, seven requiring atrial flutter ablation. A 9 Fr, 9 MHZ intracardiac echo catheter was pulled back from SVC to IVC using respiratory and ECG gating. The images, recorded on a Clearview ultrasound machine, were reconstructed using commercially available software. The intracardiac basket was placed into the atrium using the markers and fluoroscopy to allow orientation. Isochronal maps were obtained from the basket in sinus rhythm, pacing from different sites within the atrium and in atrial flutter. Isochronal maps were constructed and superimposed on the ICE image. The maps with pacing were consistent with that which was expected, confirming the validity of this approach. We were able to visualize changes in activation sequence following the placement of bidirectional isthmus block. True electroanatomic mapping is possible by the use of three-dimensional ICE reconstruction of the right atrium with electrical activation obtained from an intracardiac basket. This has significance for anatomically based arrhythmia ablations such as the ablation of atrial flutter, atrial fibrillation, with transcatheter MAZE procedures and pulmonary vein isolation. Further developments in software will allow such maps to be produced simultaneously with greater rapidity.

Adolescent↗
PubMed2005

Ablation of atrial tachycardia after surgery for congenital and acquired heart disease using an electroanatomic mapping system: Which circuits to expect in which substrate?

OBJECTIVES: The purpose of this study was to compare atrial tachycardia circuits after a range of cardiac operations. BACKGROUND: Knowledge of circuits occurring in a given postsurgical substrate should help to ablate these challenging tachycardias and develop potential preventive strategies. METHODS: We analyzed tachycardia circuits in 83 consecutive patients (60 males; median age 47 years, range 9-73) after atrial incisions undergoing ablation of atrial tachycardias. A combined strategy of electroanatomic (CARTO) and entrainment mapping was used. Fifty-two patients (63%) underwent operation for congenital and 31 (37%) for acquired heart disease. Patients were divided into subgroups based on the intervention performed in the atria: right lateral atriotomy (39 patients), left atrial (11) and superior transseptal (10) approach to the mitral valve, biatrial heart transplantation (8), Mustard (8) and Fontan (4) procedure, and other interventions (3). RESULTS: Most of the 119 tachycardias mapped were isthmus-dependent atrial flutter (66) and incisional tachycardia (30). Isthmus-dependent atrial flutter was the most frequent arrhythmia in all subgroups except for Fontan patients, in whom incisional tachycardia was most frequent. The distribution of tachycardia circuits did not differ significantly among groups. CONCLUSIONS: The observed circuits did not differ among the postsurgical substrates. Isthmus-dependent atrial flutter should be the first circuit considered in patients after atrial incisions.

Atrial Flutter↗
PubMed1977

Dissimilar atrial rhythms in a patient with the Wolff-Parkinson-White syndrome.

In this report, we present the findings in a patient who had paroxysmal supraventricular tachycardia and atrial flutter associated with the Wolff-Parkinson-White syndrome. During atrial flutter, localized atrial fibrillation was recorded in the coronary sinus (dissimilar atrial rhythms), near the accessory pathway; and during 90 minutes of observation, ventricular activation occurred solely over the normal pathway. We postulate that localized atrial fibrillation repetitively invaded the accessory pathway and rendered it refractory to conduction by flutter impulses.

Atrial Fibrillation↗
PubMed1982

[Mobile coronary unit of Florence: early care of arrhythmias not due to acute coronary insufficiency].

The aim of Mobile Coronary Care Units (M.C.C.U.) is to reduce the delay in delivering intensive care to patients with a heart attack. In the city of Florence a M.C.C.U. has been available since November 1979. During the first year the staff of the M.C.C.U. has treated 158 cases of serious cardiac arrhythmias which occurred among 486 interventions. In 94 patients cardiac arrhythmias followed an acute coronary attack. In 64 patients coronary heart disease could not be demonstrated. This study concerns the latter group of patients. The mean age was 65.2 years and 39 patients (61%) were women. The mean time from the onset of the symptoms to the arrival of the M.C.C.U. team was 3h and 2 min, whereas the mean time from the call to the arrival was 14 min. Sixty patients had atrial arrhythmias (29 atrial fibrillation, 2 atrial flutter, 22 atrial tachycardia, 7 premature atrial contractions) and 4 patients had ventricular arrhythmias (1 ventricular tachycardia, 1 ventricular flutter, 2 premature ventricular contractions). In thirty-nine patients (61%) the cardiac arrhythmia was abolished by the staff of the M.C.C.U.. Of the remaining 28 patients, 10 were brought to the hospital and 18 were left at home. None of these needed later admission to the hospital. So the treatment at home of cardiac arrhythmias has been successful in the majority of patients. Bunaftine was the antiarrhythmic drug more frequently used (23 cases, 34%) with a high percentage of success (87%). In planning medical emergency services to the community, one can envisage the use of the M.C.C.U. facilities to treat at home those arrhythmias that are not associated with an acute coronary attack.

Adult↗
PubMedDate not supplied

[Auricular flutter associated with an interatrial septal aneurysm submitted to radiofrequency ablation].

We present the case of a young man who began with type I atrial flutter, he had no response to antiarrhythmic drugs. The echocardiogram showed an atrial septal aneurysm in the region of the fossa ovalis. We performed an electrophysiologic study which showed an atrial flutter with atrial rate of 257 bpm, and 2:1/3:1 AV conduction. The flutter waves were negatives in leads II, III and a VF (type I atrial flutter). An endocardial mapping was obtained in order to localize the area of slow conduction. It was located in the isthmus of atrial tissue bounded by the inferior vena cava and the tricuspid valve annulus in the low posterior septal right atrium. In this area we applied radiofrequency energy in 10 occasions but the arrhythmia was not suppressed. With atrial pacing we achieve a concealed entrainment and then resumption of atrial flutter after cessation of pacing. After another 6 applications of radiofrequency in this same area in sinus rhythm, we paced the atrium without inducing any form of arrhythmia. He was asymptomatic 15 days later, but one month after the ablation, the flutter reappeared, we performed a second successful radiofrequency ablation. In this time he was asymptomatic.

Adult↗
PubMed2005

Surgical ablation of atrial fibrillation with a novel bipolar radiofrequency device.

OBJECTIVE: When used for epicardial ablation, unipolar devices do not predictably yield transmural scars. Bipolar radiofrequency proved highly effective on the animal model, but clinical experience is still initial. We describe acute electrophysiologic findings and follow-up results of epicardial ablation with a novel bipolar radiofrequency device. METHODS: A bipolar ablator was used to perform a simplified left atrial lesion set in 90 consecutive patients with atrial fibrillation undergoing open heart surgery. Pacing thresholds were assessed during surgery to validate 24 pulmonary vein encircling lines (12 patients). Follow-up was 100% complete. RESULTS: In 67 of 90 patients (84%), mitral valve disease was the main indication to surgery. Atrial fibrillation was continuous in 74 patients (82%) and intermittent in 16 patients (18%). Pacing threshold assessment showed a complete conduction block in 22 of 24 pulmonary vein couples (92%) after a single ablation and in all patients after doubling of the encircling lines. No complications related to the ablation procedure were recorded. The sinus rhythm restoration rate was 79% at 3 months, 87% at 6 months, and 89% (17/18 patients) at 1 year. Postablation organized arrhythmias consisted in right atrial flutter in 2 patients (2%) and left atrial flutter in 6 patients (7%). CONCLUSIONS: Epicardial ablation with bipolar radiofrequency grants acute transmurality. A simplified lesion set proved highly effective in eliminating atrial fibrillation at 1-year follow-up. Our data suggest that addition of a lesion to the mitral annulus is advisable to prevent left atrial flutter.

Aged↗
PubMed1990

Computerized activation sequence mapping of the human atrial septum.

To delineate the propagation of electrical activation in the atrial septum, atrial epicardial and atrial septal maps were recorded intraoperatively using a 156-channel computerized mapping system in 12 patients during sinus rhythm (n = 10), supraventricular tachycardia associated with septal pathways in Wolff-Parkinson-White syndrome (n = 3), atrioventricular (AV) node reentrant tachycardia (n = 4), and atrial flutter (n = 5). The epicardial and septal data were recorded simultaneously from 156 atrial electrodes, digitized, analyzed, and displayed as isochronous maps on a two-dimensional diagram of the atria. During sinus rhythm, the activation wave fronts propagated most rapidly along the large muscle bundles of the atrial septum. During supraventricular tachycardia associated with Wolff-Parkinson-White syndrome, the earliest site of retrograde atrial activation usually corresponded to the position of atrial insertion of the septal pathways. However, the earliest site of activation during orthodromic supraventricular tachycardia was different from that during ventricular pacing in 1 patient with a posterior septal accessory pathway localized by the epicardial mapping study. The data document the rationale for dividing the ventricular end of the accessory pathways (ie, the endocardial technique) rather than the atrial end (ie, the epicardial technique) in patients with Wolff-Parkinson-White syndrome. During AV node reentrant tachycardia, atrial activation data suggested that atrial tissue lying outside the confines of the anatomical AV node is a necessary link in this common arrhythmia. Thus, these atrial septal maps explain why surgical dissection, or properly positioned small cryolesions placed in the region of the AV node, can ablate AV node reentrant tachycardia without altering normal AV node function. The maps recorded during atrial flutter suggest the importance of the atrial septum as one limb of a macroreentrant circuit responsible for the arrhythmia, and imply that atrial flutter is amenable to control by surgical techniques. These studies demonstrate the details of normal atrial septal activation, the importance of the atrial septum in a variety of different atrial arrhythmias, and the basis of and potential for surgical ablation of the most common types of supraventricular arrhythmias.

Adolescent↗
PubMed2006

Left ventricular dysfunction in atrial fibrillation: restoration of sinus rhythm by the Cox-maze procedure significantly improves systolic function and functional status.

BACKGROUND: Atrial flutter or fibrillation with rapid, uncontrolled ventricular response may lead to left ventricular dysfunction, and conversion to sinus rhythm with control of heart rate can improve left ventricular ejection fraction. Little is known about the effects of the Cox-maze procedure on this form of tachycardia-induced cardiomyopathy. METHODS: Four hundred forty-three patients underwent the Cox-maze procedure from 1993 to 2002. Ninety-nine had atrial flutter or fibrillation without associated valvular or congenital heart disease, and 37 (37%) had decreased left ventricular function (ejection fraction < 0.35 in 11 [severe], ejection fraction 0.36 to 0.45 in 8 [moderate], and ejection fraction 0.46 to 0.55 in 18 [mild]). Ages of these 37 patients (34 male) ranged from 35 to 74 years (median, 55 years). RESULTS: Atrial flutter or fibrillation was present for 3 months to 19 years (median, 48 months) preoperatively, and 24 patients (65%) exhibited symptoms of heart failure. Preoperative ejection fraction ranged from 0.25 to 0.55 (median, 0.45). At last follow-up (median, 63 months), the Cox-maze procedure eliminated atrial flutter or fibrillation in all but 1 patient, and the greatest improvement was observed in patients with severe preoperative impairment (0.31 to 0.53; p = 0.01, preoperative versus follow-up), and patients with preoperative chronic atrial flutter or fibrillation (0.43 to 0.55; p < 0.05 preoperative versus follow-up). This improvement was observed immediately postoperatively and was sustained at last follow-up. Further, improvement in left ventricular function correlated with enhancement of functional status. CONCLUSIONS: In some patients, atrial flutter or fibrillation may be the cause rather than the consequence of left ventricular dysfunction. Importantly, systolic function and functional status can be significantly improved with the restoration of sinus rhythm by the Cox-maze procedure.

Adult↗
PubMed1991

Clinical decision making of critical care nurses managing computer-simulated tachydysrhythmias.

The purposes of this study were to describe the clinical decision making of critical care nurses managing computer-simulated tachydysrhythmias and to assess the major sources of error related to the management of two tachydysrhythmias: atrial flutter and ventricular tachycardia. In this descriptive study, 142 critical care nurses each completed four computerized clinical simulations (two atrial flutter and two ventricular tachycardia). Simulation performance was measured by proficiency score (comparison with expert performance), patient outcome (cure or die), and amount of data collected before the first intervention. Mean proficiency scores were 51% for atrial flutter and 35% for ventricular tachycardia. Thirteen percent of the atrial flutter and 35% of the ventricular tachycardia simulations ended in patient death. Failure to recognize ventricular tachycardia and unfamiliarity with second- and third-line treatments were major sources of error. Medication errors were the cause of death in 87% of the simulations ending in patient death. These results document the need for emphasis on dysrhythmia management in the critical care curriculum.

Arrhythmias, Cardiac↗
PubMed1997

Efficacy and safety of sotalol in patients with refractory atrial fibrillation or flutter.

Sotalol's usefulness in treatment of atrial fibrillation and atrial flutter is unproven. This study evaluated (1) the efficacy of sotalol in preventing recurrences of paroxysmal atrial fibrillation or atrial flutter and controlling ventricular rate (in chronic atrial fibrillation or relapse of paroxysmal atrial arrhythmias), (2) the safety of sotalol, and (3) predictors of sotalol efficacy. Thirty-three patients, 28 with paroxysmal and five with chronic atrial fibrillation or atrial flutter, received an average dose of 265 +/- 119 mg of oral sotalol per day. During a 10 +/- 12 month follow-up, recurrence rate for paroxysmal arrhythmia was 64%, with a 50% recurrence at 4.6 months. For patients with chronic atrial fibrillation, ventricular rates were well controlled with sotalol administration (136 +/- 33 beats/min versus 88 +/- 23 beats/min; p = 0.04). No patient with chronic atrial fibrillation converted to sinus rhythm during the study. Side effects necessitated sotalol discontinuation in three patients. By multivariate analysis, younger age, higher ejection fraction, and absence of hypertension independently predicted sotalol efficacy.

Aged↗
PubMed1991

Successful surgical treatment of atrial fibrillation. Review and clinical update.

Atrial fibrillation is the most common of all sustained cardiac arrhythmias, yet it has no effective medical or surgical therapy. During the past decade, multipoint computerized electrophysiological mapping systems were used to map both experimental and human atrial fibrillation. On the basis of these studies, a new surgical procedure was developed for atrial fibrillation. Between September 25, 1987, and July 1, 1991, this procedure was applied in 22 patients with paroxysmal atrial flutter (n = 2), paroxysmal atrial fibrillation (n = 11), or chronic atrial fibrillation (n = 9) of 2 to 21 years' duration. All patients were refractory to all antiarrhythmic medications, and each patient failed to receive the desired therapeutic benefits of an average of five drugs administered preoperatively. There were no operative deaths and all perioperative morbidity resolved. All 22 patients have been successfully treated for atrial fibrillation with surgery alone. Three patients developed one late isolated episode of atrial flutter at 5, 6, and 15 months postoperatively, and each of these patient's symptoms is now controlled by a single antiarrhythmic drug. Preservation of atrial transport function has been documented in all patients postoperatively, and all have experienced marked clinical improvement.

Adult↗
PubMed1996

Effect of varying atrial sensitivity, AV interval, and detection algorithm on automatic mode switching.

UNLABELLED: Automatic mode switching (AMS) is absolutely dependent on atrial tachyarrhythmia detection. The effects of programming several features that could influence tachyarrhythmia detection were assessed in 18 patients (six women; mean age 64 years) with pacemakers having AMS capability. The atrial electrogram amplitude in sinus rhythm at implant (SR-EGM), last measured atrial sensing threshold prior to tachycardia (A-SENS), and atrial sensing threshold for effective AMS during atrial tachyarrhythmia (AMS-SENS) were obtained. Additionally, ten patients had AV intervals increased from 60 to 200 ms, while seven patients had detection algorithms made more stringent from 5 beats at 150 beats/min to 11 beats at 200 beats/min to assess their effects on AMS efficacy. RESULTS: Sensitivities:Mean SR-EGM = 3.55 mV; mean A-SENS = 2.06 mV; and mean AMS-SENS = 1.46 mV. Fourteen patients developed atrial fibrillation and four atrial flutter. Thirteen of 14 patients who developed atrial fibrillation sensed adequately at > or = 1.0 mV in normal sinus rhythm (NSR), but only six patients had effective AMS at these settings in atrial fibrillation. Three of four patients who developed atrial flutter had effective AMS at > or = 2.0 mV. AV Interval:AMS was effective in eight of ten patients at AV intervals up to 200 ms. One patient lost AMS at an AV interval of 120 ms. Algorithm: In two of seven patients, AMS was not effective if the detection algorithm was more stringent than five beats at 150 beats/min. CONCLUSIONS: (1) In atrial fibrillation, effective AMS requires more sensitive atrial settings than in NSR; (2) AV intervals as short as 120 ms can interfere with AMS function; and (3) More stringent detection algorithms may be inappropriate for effective AMS function.

Algorithms↗
PubMed2001

Arrhythmias after pediatric lung transplantation.

Atrial arrhythmias have been reported after congenital heart surgery involving extensive atrial suture lines. Experimental studies involving bilateral lung transplantation (Tx) suggest that the left atrial suture lines predispose to atrial flutter. The overall incidence and type of arrhythmias after pediatric lung Tx have not previously been described and therefore the purpose of this study was to prospectively screen and describe arrhythmias in a subset of our lung transplant population. Over a 1-yr study period, all recipients of bilateral lung Tx were admitted to a full-disclosure telemetry unit. Single-lead electrocardiograms were recorded continuously and reviewed daily via a beat-by-beat analysis. A total of 314 patient days (range 9-93, median 43 days) were recorded from seven patients. The incidence of arrhythmias observed per total patient days included junctional escape rhythm (4.8%), non-sustained ventricular tachycardia (4.1%), accelerated junctional (2.5%), sinus bradycardia (2.2%), non-sustained supraventricular tachycardia (1.3%), ectopic atrial tachycardia (1.0%), sustained ventricular tachycardia (0.3%), junctional ectopic tachycardia (0.3%), and second degree heart block (0.3%). No patient had sustained supraventricular tachycardia, atrial flutter, atrial fibrillation, or complete heart block. Arrhythmias were treated in two patients. During the follow-up period, one patient received amiodarone for ventricular tachycardia (which was also noted and treated prior to transplant). We conclude that among pediatric lung transplant recipients admitted for their transplant surgery, arrhythmia is uncommon and rarely requires therapy.

Adolescent↗
PubMed2005

Fontan conversion with arrhythmia surgery.

OBJECTIVE: Hemodynamic abnormalities and refractory atrial arrhythmias in patients late after the Fontan operation result in significant morbidity and mortality. We reviewed our experience with Fontan conversion and concomitant arrhythmia surgery. METHODS: Between January 1996 and February 2004, 16 patients underwent Fontan conversion and arrhythmia surgery. Mean age at the initial Fontan operation was 5.1+/-3.5 (range: 2-15) years and mean age at Fontan conversion was 17.0+/-5.8 (range: 6-30). The initial Fontan operations were atriopulmonary connections in 14 patients, extracardiac lateral tunnel in 1, and intracardiac lateral tunnel in 1. The types of arrhythmia included atrial flutter in 10 patients and atrial fibrillation in 3. Fontan conversion operation was performed with intracardiac lateral tunnel in 5 patients and extracardiac conduit in 11. Arrhythmia surgery included isthmus cryoablation in 10 patients and right-sided maze in 3. RESULTS: There has been no mortality. At Fontan conversion operation, 7 patients required permanent pacemaker. All patients have improved to New York Heart Association class I or II. With a mean follow-up of 26.9+/-30.6 (range:1-87) months, 16 patients had sinus rhythm, 2 patients had transient atrial flutter which was well controlled, and 2 patients required permanent pacemaker during follow-up. CONCLUSIONS: Fontan conversion with concomitant arrhythmia surgery and permanent pacemaker placement is safe, improves New York Heart Association functional class, and has a low incidence of recurrent arrhythmias. In most patients, concomitant permanent pacemakers are needed.

Adolescent↗
PubMed1989

[A case of sick sinus syndrome, considered to develop to atrial standstill].

A 25 year old man was admitted to our hospital because of dizziness and bradycardia. Physical examination was normal except for an irregular pulse of 90 beats/min. Chest X-ray film showed no cardiomegaly and no pulmonary congestive changes. ECG showed 2:1 or 3:1 atrial flutter on admission. After atrial flutter was terminated spontaneously, ECG revealed absent P waves, a QRS interval of 0.10 seconds, and A-V junctional rhythm with irregular R-R interval ranging from 1.20 to 2.12 seconds. At times, cardiac arrest was noted. Esophageal electrocardiogram also failed to demonstrate atrial activity while A-V junctional rhythm continued. Mitral valve echocardiogram lacked A point, and then ä waves were absent in both the right atrial and pulmonary capillary pressure recordings. Transient atrial standstill was suspected from these findings, so that electrophysiological study was performed. Right atrial electrogram revealed complete absence of atrial activity. His bundle electrogram revealed H-V prolongation [80-83 msec]. Right atrial pacing was attempted at several atrial sites, including the high lateral, middle lateral, low lateral right atrium, and low right atrial septum. Atrial activity could be elicited with stimulus strength of 3 to 5 volts. These atrial pacing thresholds were mild or moderately higher than usual. After the cessation of atrial pacing at 90 beats for two minutes, the recovery time of the first beat prolonged to 8.46 second. We considered that this case was sick sinus syndrome in young adult which revealed generalized disturbance of conduction system including the atrial muscle, and would develop to atrial standstill in the near future.

Adult↗
PubMed2003

Electrocardiographic effects of intravenous cocaine: an experimental study in a canine model.

Cocaine abuse causes cardiac dysfunction. Acute intravenous administration of cocaine may lead to development of severe arrhythmias, conduction abnormalities, ST-T changes, and sudden death. Understanding arrhythmogenesis due to cocaine may provide a therapeutic approach to reduce morbidity and mortality. We studied the arrhythmogenic activity and other electrocardiographic abnormalities resulting from an intravenous bolus of cocaine. Baseline and postanesthetic electrocardiographic findings were compared with those after administration of intravenous bolus of various doses of cocaine hydrochloride in 20 dogs. The study was done in three phases (phase I: low dose of cocaine [1 mg/kg, 15 experiments]; phase II: medium dose [2 mg/kg, 30 experiments]; and phase III: high dose [5-7 mg/kg, 10 experiments]). Plasma levels of cocaine were estimated. The low dose induced sinus bradycardia, sinus arrhythmia, atrial ectopic, wandering pacemaker, unifocal ventricular premature contractions, and ventricular couplets. The medium dose generated moderately severe arrhythmias that were of supraventricular origin. Atrial flutter and atrial fibrillation were observed in two experiments each. Ventricular arrhythmias were manifested as unifocal, multifocal, interpolated ventricular premature contractions as well as bigeminy, trigeminy, couplets, and salvos. The high dose of 5-7 mg/kg increased electrocardiographic intervals and caused ST-segment elevation as well as serious life-threatening arrhythmias. Three of the dogs developed sustained ventricular tachycardia followed by ventricular flutter-fibrillation and death.

Animals↗
PubMed1995

A prospective study of electrical cardioversion for sustained tachycardias by emergency unit personnel.

Acute symptomatic tachyarrhythmias are commonly seen by emergency unit personnel. Electrical cardioversion is often used at Groote Schuur Hospital to treat such patients because of concerns about the safety and efficacy of intravenous anti-arrhythmic agents. All patients presenting with acute symptomatic tachyarrhythmias who were managed only by the staff of the Emergency Unit were entered into the study to assess the efficacy and safety of direct current (DC) cardioversion. Those with sinus tachycardia or atrial fibrillation of more than 24 hours' duration were excluded. Staff, on joining the unit, were instructed in the use and technique of DC cardioversion, and given simple guidelines for the management of acute tachyarrhythmias. Fifty-three patient events were seen over a period of 16 months: 7 patients had ventricular tachycardia, 21 had atrial flutter, 20 had paroxysmal junctional re-entry tachycardia, 4 had atrial fibrillation and 1 had multifocal atrial tachycardia. Fifty-two were successfully converted to sinus rhythm. One patient with atrial flutter and 9 with paroxysmal junctional re-entry tachycardia reverted after undergoing vagal manoeuvres or receiving intravenous verapamil. Of the remaining 43 patients, 42 (98%) were cardioverted with synchronised DC shock under midazolam sedation (7/7 ventricular tachycardia, 20/20 atrial flutter, 11/11 paroxysmal junctional re-entry tachycardia, 4/4 atrial fibrillation, 0/1 multifocal atrial tachycardia). Four patients had their sedation electively reversed with flumazenil. No complications occurred. DC cardioversion was only considered inappropriate in the 1 patient with multifocal atrial tachycardia. This study shows that if simple guidelines are followed, non-cardiologist junior medical personnel can safely and effectively manage sustained, acute, symptomatic tachyarrhythmias by employing DC cardioversion as and when appropriate.

Atrial Fibrillation↗
PubMed1999

Mapping of atrial activation with a noncontact, multielectrode catheter in dogs.

BACKGROUND: Endocardial mapping of sustained arrhythmias has traditionally been performed with a roving diagnostic catheter. Although this approach is adequate for many tachyarrhythmias, it has limitations. The purpose of this study was to evaluate a novel noncontact mapping system for assessing atrial tachyarrhythmias. METHODS AND RESULTS: The mapping system consists of a 9F multielectrode-array balloon catheter that has 64 active electrodes and ring electrodes for emitting a locator signal. The locator signal was used to construct a 3-dimensional right atrial map; it was independently validated and was highly accurate. Virtual electrograms were calculated at 3360 endocardial sites in the right atrium. We evaluated right atrial activation by positioning the balloon catheter in the mid right atrium via a femoral venous approach. Experiments were performed on 12 normal mongrel dogs. The mean correlation coefficient between contact and virtual electrograms was 0.80+/-0.12 during sinus rhythm. Fifty episodes of atrial flutter induced in 11 animals were evaluated. In the majority of experiments, complete or almost complete reentrant circuits could be identified within the right atrium. Mean correlation coefficient between virtual and contact electrograms was 0.85+/-0.17 in atrial flutter. One hundred fifty-six episodes of pacing-induced atrial fibrillation were evaluated in 11 animals. Several distinct patterns of right atrial activation were seen, including single-activation wave fronts and multiple simultaneous-activation wave fronts. Mean correlation coefficient between virtual and contact electrograms during atrial fibrillation was 0.81+/-0.18. The accuracy of electrogram reconstruction was lower at sites >4.0 cm from the balloon center and at sites with a high spatial complexity of electrical activation. CONCLUSIONS: This novel noncontact mapping system can evaluate conduction patterns during sinus rhythm, demonstrate reentry during atrial flutter, and describe right atrial activation during atrial fibrillation. The accuracy of electrogram reconstruction was good at sites <4.0 cm from the balloon center, and thus the system has the ability to perform high-resolution multisite mapping of atrial tachyarrhythmias in vivo.

Animals↗